Question

Which statement correctly describes the differences between positive and negative acceleration? Positive acceleration describes a change in speed; negative acceleration describes no change in speed. Positive acceleration describes no change in speed; negative acceleration describes a change in speed. Positive acceleration describes an increase in speed; negative acceleration describes a decrease in speed. Positive acceleration describes a decrease in speed; negative acceleration describes an increase in speed.

Answer 1

The correct answer is - Positive acceleration describes an increase in speed; negative acceleration describes a decrease in speed.

Answer 2

Positive acceleration describes an increase in speed; negative acceleration describes a decrease in speed.

Step-by-step explanation:

Acceleration is defined as:

`a=(v-u)/(\Delta t)`

where

v is the final velocity

u is the initial velocity

`\Delta t` is the time taken for the change in velocity to occur

The value of
`\Delta t` is always positive, so the sign of the acceleration depends on the numerator. More specifically, we have two situations:

- if
`v > u`, then it means that the final velocity is greater than the initial velocity, so the acceleration is positive and the speed is increasing

- if
`v < u`, then it means that the final velocity is smaller than the initial velocity, so the acceleration is negative and the speed is decreasing